SU1284001A1 - Device for controlling contrast - Google Patents

Abstract

The invention relates to television and provides promotion. control accuracy. The input video signal (BC), amplified N times by amplifier I, is fed to the marker shaper (FMS) 2. FMS on the reference voltage and, and Ug, coming from source 3 of the reference voltage and specifying the required range of allocated levels of aircraft, generates control pulses of switches 4, 5. As a result, through switch 4 at times, respectively. selected range of aircraft levels, passes enhanced aircraft. Further, this video signal, limited in limiter 6 by the CD level, goes to the adder 8. Through these switch 5, the input aircraft does not pass at these moments. The BC passing through switch 5 is limited in level limiter 7, respectively. signal tvmovogo field in the input BC, and is fed to another input of the adder 8. The output signal of the adder 8 eliminates the dependence of the accuracy of adjusting the contrast of the levels of the sun to the contrast of black and white differential from their amplitude in the original sun. 2 Il. (Ls

Description

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The invention relates to a television technique and can be used for: raising the image contrast by converting a video signal.

The purpose of the invention is to improve the accuracy of regulation.

Figure 1 is an electrical block diagram of a device for adjusting contrast; figure 2 - timing diagrams of video signals when adjusting the contrast.

The device for adjusting the contrast (Fig. 1) contains the amplifier 1, the shaper 2 of the marker signal, the source 3 of the reference voltage, the first and second switches 4 and 5, the first and second limiters 6 and 7, the adder 8.

The contrast adjustment device operates as follows.

At the input of the device comes a signal Ug (Fig.2A). In amplifier 1, the input video signal is amplified N times (signal U, Fig.2 &) and goes to the first inputs of the first switch 4 and shaper 2 of the marker signal, the second and third inputs of which receive the reference voltage POR, and Ujjjjj - boomey range of allocated video signal levels. At the first and second outputs of the marker maker 2, positional pulses of highlight e appear (F1x video signal levels U, j (FIG. 2b) and their inverted values, which control the first and second switches 4 and 5, respectively. At the output of the first switchboard. 4 shows the video signal U (FIG. 2, for forming which the reference voltage UOE supplied to the second input of the first switch 4, you

Borrowed by the condition Ug h 6 U

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 mi n From the output of the first switch 4

The video signal levels U (Fig. 2, d) are fed to the input of limiter 6, in which they are limited by the level UQ. Received, video signal U 0 (fig, 2.0.) Goes further to the first input of the adder. At the same time, at the output of the second switch 5, a video signal Uj appears (Fig. 2e), which

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It is fed to the input of the second limiter 7, the control input of which receives the reference voltage W4, the value of which corresponds to the level of the dark field signal in the input video signal. At the output of the adder 8, the required video signal Ugy is formed (Fig. 2g), which eliminates the dependence of the accuracy of adjusting the contrast of the video signal levels to the contrast of the black-and-white difference on their amplitude in the original video signal when the external control signal changes.

Claims (1)

Invention Formula A device for adjusting KoHt-rastry, containing in series the first limiter and adder, as well as the amplifier, whose input is the device input, and the source of the reference voltage, the first output of which is connected to the control input of the first limiter, and the control input An input of an external control signal, characterized in that, in order to improve the control accuracy, a marker generator has been introduced, the first, second and third inputs of which are connected respectively to the amplifier output, the first and second outputs of the reference voltage source, and the first switch, the first, second and control inputs of which are connected respectively to the amplifier output, to the third output of the reference voltage source and to the first output of the marker of the marker signal, and the encoder connected to the signal the input of the first limiter, serially connected to the second switch, the first, second; and the control inputs of which are connected respectively to the input of the amplifier, with the third output of the reference voltage source and the second output of the marker generator, and the second limiter, the control input of which is connected to the fourth output of the voltage source, and the output connected to the second input of the adder. but and,, Well A / x I I. IL fu & .2